A wearable device (head-mounted display) that is worn on the head of the user and projects an image within the field of view of the user has been known. For example, JP-A-2005-43701 and JP-A-2006-3879 disclose technology that relates to such a wearable device.
JP-A-2005-43701 discloses a head-mounted display in which three independent contact elements (to be in contact with the head) are disposed to an end portion of a headband, the three contact elements are provided to a base member to form a triangular shape within a contact surface, and the base member and the headband are coupled to each other to have a degree of freedom including rotation around two axes.
JP-A-2006-3879 discloses a pupil-division see-through-type head-mounted display. The technology disclosed in JP-A-2006-3879 significantly reduces the size of an eyepiece element (eyepiece window) that projects (emits) a virtual image of a display image to implement see-through display (i.e., display in which the external field of view and the display image overlap each other), and see-around display (i.e., display in which a wide external field of view is provided).